The overall goal of this project is to determine the ability of 1H MRI/MRS at 4T to localize the epileptogenic focus in partial epilepsy and to predict the outcome of seizure surgery. This application proposes a continuing effort to improve the outcome of seizure surgery by better presurgical localization of intractable partial epilepsy using state of the art neuroimaging techniques. Specifically, we will determine the predictive 'Value added" of MRI (structural, arterial spin perfusion, and diffusion tensor imaging) and MRS (single voxel and 3D) imaging to the diagnostic evaluation of refractory epilepsy using a 4 Tesla scanner that will be optimized for investigation of neurodegenerative disease. This project will study patients with non-lesional, unifocal, medically refractory, localization related epilepsy. These techniques will be directed at two groups of patients with intractable epilepsy who are being evaluated for seizure surgery (numbers for 5 years): 1) patients with medial temporal lobe epilepsy with and without MRI evidence of mesial temporal sclerosis (n=80), 2) patients with non-lesional neocortical epilepsy (may include cortical malformations) (n=80). Post-operative surgical outcome will be analyzed in relation to the pre-operative neuroimaging findings. Hypotheses: 1) for patients with medically refractory complex partial seizures arising from either the medial temporal lobe or from neocortical regions, structural, perfusion, diffusion and MRS imaging at 4T will be a more sensitive measure of seizure lateralization/localization than conventional MRI performed at 1.5T;2) for these two patient groups, MRI and MRS measures at 4T that are concordant with the lateralization by video/EEG telemetry will have significantly better post surgical outcomes than patients without concordance. All studies will be performed in a systematic, prospective, blinded, and controlled manner to predict the patients that respond best to seizure surgery. The significance of these studies is that the use of newly developed MRI and MRS techniques at high field strength will lead to improved epilepsy surgery outcomes and will reduce unnecessary surgery in patients with intractable epilepsy.